#include<iostream>
using namespace std;
const int N=1e7;
const int mod=1e9+7;
int a[N],b[N];
long long n;
int main(){
	scanf("%lld",&n);
	for(int i=3;i<n;i++){
		a[i]=(a[i-1]*2+b[i-1])%mod;
		b[i]=
	}
} 
